Thread feed control device for textile machinery



A ril 21, 1964 Y. JUILLARD 3,129,902

THREAD FEED CONTROL DEVICE FOR TEXTILE MACHINERY Filed March 20, 1962 gu un United States Patent f 3,129,902 THREAD FEED CONTROL DEVICE FOR TEXTILE MACHINERY Yves Juillard, Mulhouse, Haut-Rhin, France, assignor to Societe Alsacienne de Constructions Mecaniques, Mulhouse, Haut-Rhin, France, a company of France Filed Mar. 20, 1962, Ser. No. 181,102 Claims priority, application France Mar. 22, 1961 2 Claims. (Cl. 242-449) This invention relates to an improved device for con thread tension in many cases interfere with the proper performance of subsequent processing steps to which the thread may have to be subjected or may be objectionable for various other reasons. It is an object of this invention to provide an improved thread feed control device of very simple and yet effective construction that will act to control the tension in a thread despite large acceleration and deceleration forces to which the thread may be subjected. Other objects are to provide such a thread control device that will be very easily adjustable; that will operate effectively even in case of a knot or nep or other irregularity at a point of the thread; and one that can conveniently and efiiciently be associated with a conventional stopper device for arresting the feed of thread or performing some other safety function in case of thread breakage.

A more specific object is to provide an improved thread feed or tension regulator device especially adapted for use in connection with the weft shooting operations in a fast weaving frame or loom.

In fast shuttle-less looms in which the picks of weft are shot across the shed formed in the warp yarn by means of a pair of cooperating needles which are cyclically projected into and retracted out of the shed from both sides simultaneously so as to transfer the weft yarn from one to the other of said needles at each weaving cycle, the weft yarn is periodically exposed to large accelerations and decelerations. Specifically, the pick of Weft y-arn initially at zero velocity is first accelerated and then decelerated as it is carried by one needle from outside the shed to a point midway across the breadth of the shed at which it is to be transferred to or picked off by the other needle. At this point the yarn again remains stationary for a brief period and then is accelerated by the other needle until it has been brought out of the shed on the opposite side, whereupon the thread movement is again arrested. Thus in each weaving cycle there are two periods of acceleration respectively followed by two periods of deceleration. Even though the weight, or inertia at rest, of the thread may be very slight, at the high velocities involved in modern looms such rapid variations in velocity give rise to considerable inertia effects resulting in large variations in thread tension. It is desirable however that the tension in the weft thread should remain largely constant throughout the weaving cycle. This is important in order to ensure that the transfer of the weft between the shooting needles shall occur reliably and smoothly, that the outer ends of pick at the selvedges of the fabric shall be uniform in length, and that the final tension in the weft yarn in the woven fabric shall consistently retain a desired value. Objects 3,129,002 Patented Apr. 21, 1964 of this invention include the attainment of these advantageous results, and hence also the provision of woven fabrics of improved quality with looms of the specified type.

In accordance with an aspect of the invention, there is provided a thread feed control or regulator device comprising means providing a smooth surface, thread guide means engageable with the thread to define a path of thread displacement generally parallel to said surface, at least one low-inertia presser element supported above said surface and engaging a side of the thread remote from said surface, and means biasing said presser element towards said surface with a predetermined moderate force whereby in periods of thread acceleration the resulting thread tension overcomes the biasing force to lift the presser element off said surface while in periods of thread deceleration the resulting drop in thread tension allows the presser element to press the thread down against the surface thereby maintaining the thread tension beyond the control device at a positive value.

The above and other aspects and features of the invention will be made clear as the disclosure proceeds with reference to the accompanying drawings showing an exemplary embodiment of the invention selected by way of illustration but not of limitation and wherein:

FIG. 1 is a perspective front view of the improved thread feed control device or tension regulator shown in the condition assumed thereby during a period of deceleration of the thread;

FIG. 2 is a front view of the same device in the condition assumed during a period of acceleration;

FIG. 3 is a view similar to that of FIG. 2 in the condition assumed on breakage of the thread; and

FIG. 4 is a sectional view on the line IVIV of FIG. 3.

The device illustrated comprises a baseplate 401 arranged to be mounted at any convenient position on the textile machine with which the device is to be used. While the plate 401 is here shown vertical it is to be distinctly understood that this is by no means essential and that the plate might well be mounted horizontal or in any other angular position. Hence also it is expressly indicated at this point that terms indicating spatial relationships such as above, below and the like, as used in the specification and the claims, are to be understood in a relative rather than in an absolute sense and cannot be deemed to limit the scope of the invention.

Secured to the baseplate 401 near one side is a table plate 402 having a smooth upper surface normal to the surface of the baseplate 401. Projecting from the plate 401 at a common distance from the surface of table 402 and spaced in a direction parallel to said surface are a number of, herein three, thread guides 403, 404, 405 in the conventional form of hooks or eyes through which is threaded a yarn 407 the feed of which is to be regulated by the device.

Projecting from the baseplate 401 above the row of guides and positionally adjustable on the baseplate through means to be presently described is a supporting plate or bar 413 having secured to the lower surface by any suitable means, e.g. screws, one end of each of two presser elements in the form of light weight leaf springs 411 and 412 of low spring rate, which are curved downwards to project in between the guides 403 and 404, and guides 404 and 405 respectively, with the rounded lower ends of said leaf springs bearing resiliently against the upper surface of table plate 402 as shown, under light adjustable spring pressure.

One convenient means for mounting the presser spring elements 411, 412 for ready adjustment of their spring pressure is here shown as comprising a magnetic mounting for the supporting plate or bar 413. More specifically, the plate 413 may be made of a ferromagnetic material and retained in an adjustable position on baseplate 401 by the attraction of a pair of magnetic pole members 414, 415. In this example the magnetic members 414, 415 are permanent magnets and are received in suitable spaced holes formed through baseplate 401 and in cup-like socket-members 416, 417 secured to the back of the baseplate with screws 418 in line with the holes, in such a manner that the front faces of the magnetic members 414, 415 lie flush with the front surface of baseplate 401. Moreover, in the illustrated example there are provided a pair of set screws 421, 422 engaging tapped holes in respective lugs 423, 424 projecting from baseplate 401 above the magnets so that the tips of the screws can bear adjustably against the upper surface of supporting bar 413.

It will readily be understood that with the mounting arrangement described, the bearing pressure exerted by each of the leaf springs 411, 412 against the thread 407 and table surface 402 can quickly and easily be adjusted by simply shifting the supporting bar 413 across the faces of the magnets 414, 415, with fine adjustment being possible by selective action on screws 421, 422. It will be noted that the arrangement permits of differential or independent adjustment of the pressure of each spring, as by positioning the bar 413 in an angled position nonparallel to the surface 402 eg as shown in chain lines in FIG. 2.

Shown mounted on one side (the thread output side) of the table plate 462 is a generally conventional thread break sensing device in the form of a microswitch 431 having an actuating arm 432 projecting so as to be engaged by the outgoing thread 407.

In operation, it will be understood that the spring characteristics of the presser elements or leaf springs, 411, 412 are so selected and the position of their support 413 is so adjusted, that the pressureexerted by said elements against the surface of table 402 is just sufficient to clamp the thread 407 to said surface during periods where the thread is running slack, as during periods of deceleration in the thread feed displacement, so that during such periods the kinetic energy given up by the decelerating thread is absorbed as friction with the clamping surfaces of the table and presser elements. At the same time, the pressure is so light that during periods of increased thread tension, as when the thread is accelerating, the tension force will overcome the spring pressure and lift the lower ends of the presser elements off the surface of table 402.

Thus, assume the thread is accelerating as by being positively pulled towards the left in the direction of arrow 1 in FIG. 2, by a pulling force applied to the thread at a point beyond the control device, e.g. by a weftshooting needle in a loom of the type hereabove described. The thread is placed under substantial tension and the presser elements 411, 412 are moved away from the surface 402, as shown'in FIG. 2, so that the thread is no longer clamped between the opposing surfaces of the table and the presser elements, but is only subjected to the very low friction exerted on its upper side by the rounded ends of the leaf springs. Should however the pulling force applied to the thread decrease, as when the shooting needle carrying the thread across the shed of warp yarn in the loom is coming to a stop, then there is a corresponding drop in thread tension such that the resulting thread tension is no longer able to overcome the spring force of the presser elements 411, 412, which thereupon clamp the thread against the table surface 402 as shown in FIG. 1. The device now acts as friction brake which absorbs the kinetic energy stored in the thread and maintains the tension in the thread beyond the device at a predetermined positive value. The thread is thus prevented from kinking beyond the device and its uniform tension of delivery ensures smooth trouble-free operation of the loom or other textile machine with which the device is associated.

In case of a break occurring in the thread beyond the control device as shown in FIG. 3, the switch finger 432 is released to actuate the switch for stopping the thread delivery and/or effecting any other desired function.

The provision of two presser elements in tandem, as here shown, is extremely desirable for the following reason. Should a knot, nep, kink, or other excess in thickness occur at any point of the thread during a deceleration period (FIG. 1), this may tend to lift the leading presser element 412 off the table surface; however since the other presser element 411 generally remains in engagement with the table surface at that time the output tension will not substantially decrease and by the time the knot reaches the other presser element 411 the first element 412 will generally have resumed its normal position.

It will be understood that various changes may be made in the exemplary embodiment shown and described without departing from the scope of the invention. Thus, while the provision of two presser elements in tandem has the important advantage indicated above, a single presser element may be used, or more than two presser elements. The number of thread guides provided may be varied correspondingly. The adjustable mounting associated with adjusting screws, may assume various other forms even though the mounting arrangement here shown has been found to be especially advantageous in practice.

What is claimed is:

1. A tension device for a weft thread to be supplied to a shuttleless weaving loom, comprising a stationary base plate, a table portion projecting from said baseplate and providing a smooth even surface normal to said baseplate, a plurality of guide members projecting from said baseplate and engageable with a thread to define a straight path of thread displacement extending in spaced parallel relationship to said smooth even surface, an adjustable bar member supported from said baseplate above said guide members, said bar member having a face opposite said smooth even surface of said table portion, a pair of leaf springs of light spring rate having one of their ends attached to longitudinally spaced points of said face of said bar member and having their free ends projecting toward said smooth even surface between two successive guide members, said leaf springs having rounded free end portions engageable with said thread whereby to urge the thread sections extending between the individual guide members toward said smooth even surface and force the thread to follow a sinuous path, and means for adjusting the position of said bar member both in over-all spacing relative to said smooth even surface and in angular relation with respect thereto.

2. The device claimed in claim 1, including magnetic means for adjustably supporting said barfrom said baseplate.

References Cited in the file of this patent UNITED STATES PATENTS 680,682 Baldwin Aug. 20, 1901 1,580,960 Cheney Apr. 13, 1926 1,627,292 Matthews et al. May 3, 1927 2,225,154 Javery Dec. 24, 1940 2,977,996 Ancet et .al. Apr. 4, 1961 3,020,934 Waters Feb. 13, 1962 FOREIGN PATENTS 28,003 Great Britain of 1910 

1. A TENSION DEVICE FOR A WEFT THREAD TO BE SUPPLIED TO A SHUTTLELESS WEAVING LOOM, COMPRISING A STATIONARY BASE PLATE, A TABLE PORTION PROJECTING FROM SAID BASEPLATE AND PROVIDING A SMOOTH EVEN SURFACE NORMAL TO SAID BASEPLATE, A PLURALITY OF GUIDE MEMBERS PROJECTING FROM SAID BASEPLATE AND ENGAGEABLE WITH A THREAD TO DEFINE A STRAIGH PATH OF THREAD DISPLACEMENT EXTENDING IN SPACED PARALLEL RELATIONSHIP TO SAID SMOOTH EVEN SURFACE, AN ADJUSTABLE BAR MEMBER SUPPORTED FROM SAID BASEPLATE ABOVE SAID GUIDE MEMBERS, SAID BAR MEMBER HAVING A FACE OPPOSITE SAID SMOOTH EVEN SURFACE OF SAID TABLE PORTION, A PAIR OF LEAF SPRINGS OF LIGHT SPRING RATE HAVING ONE OF THEIR ENDS ATTACHED TO LONGITUDINALLY SPACED POINTS OF SAID FACE OF SAID BAR MEMBER AND HAVING THEIR FREE ENDS PROJECTING TOWARD SAID SMOOTH EVEN SURFACE BETWEEN TWO SUCCESSIVE GUIDE MEMBERS, SAID LEAF SPRINGS HAVING ROUNDED FREE END PORTIONS ENGAGEABLE WITH SAID THREAD WHEREBY TO URGE THE THREAD SECTIONS EXTENDING BETWEEN THE INDIVIDUAL GUIDE MEMBERS TOWARD SAID SMOOTH EVEN SURFACE AND FORCE THE THREAD TO FOLLOW A SINUOUS PATH, AND MEANS FOR ADJUSTING THE POSITION OF SAID BAR MEMBER BOTH IN OVER-ALL SPACING RELATIVE TO SAID SMOOTH EVEN SURFACE AND IN ANGULAR RELATION WITH RESPECT THERETO. 